Keeping track of tire rotation

In the past, I've kept track of tire rotation by marking the tires with chalk. Keeping track of which tire was in which position is also useful if one switches between winter tires and summer tires. Later when I found chalk isn't a good solution, I used tape (which is not very good because it doesn't stick well to tires but sticks better to clean wheels) or a tag tied to the wheel with string. Now, I have a better method.

I look at the tires for the date code. It is after the serial number and clearly looks heat stamped on, unlike the molded serial number. The format after the year 1999 is a 4 digit code. The first two digit is the week of the year produced and the last two digits corresponds to the year. For example 0320 would indicate that the tires were made in the 3rd week of 2020. This date code is only partly helpful because most of one's tires are likely to have been made in the same week. I currently have two tires made in one week and two tires made a different week.

To further differentiate the tires, I record the position of the valve stem to the writing on the tire. For example, the valve stem might be close to the brand name, for example, Pirelli. Or the valve stem might be close to the model name, for example ExtremeContact DW or maybe the size of the tire.

If one has directional tires, there will be a molded arrow probably with the words "rotation ->". If so, then such tire has to be on one side of the car, further differentiating each tire.

If, by chance, two tires have the same date code and the same position of the valve stem then I would probably just tie a string to the wheel or tie a tag to it.

I have two separate set of wheels, one for winter and one for the rest of the year. If one only has one set of wheels and is changing between winter and summer tires, then other than the date code, there is little to differentiate which tire is the right or left, front or back. In that case, I would tie a string completely around the tire (tie around the narrow side, not the circumference)

I have always been wary of rotating tyres, and here's why.
The Saab is front wheel drive so the fronts wear faster than the rears, approximately twice as fast in my case.
The light loading at the rear means the best tyres should be at the back but, assuming we started with four new tyres, they will be half worn by the time the fronts need to be replaced. In my mind that is good enough to leave them there and just fit new to the front. The reason for having the best tread on the back is to delay the point where they lose grip but very few of us drive anywhere near the limit, even for tyres worn near to the legal limit (here) of 1.6mm and I never let a tyre get that far.

If I rotate the tyres I will, if I get it "right", need four new tyres at the same time (£600 for my car). Now why would I want to be buying four new tyres every 18 months when I could just as easily buy two every year? I have used this method of non-rotaion for over 40 years and it seems to work, I rarely have to buy four tyres at the same time and I can budget for almost exactly when I will need them.

Of course, if you really want to go to the trouble of rotating your tyres please don't let me stop you.

Geoffr's method works except I usually don't like the tires that come with a car. His method works better starting with the second set of tires.

I keep track of tire positions because I have separate winter and summer tires. When putting on the other set, I want to know which tire was where, even if no rotation is planned.

I put my tires in bags and I've marked the bags with the tire position. I rotate after taking the tires out and rotate according to http://mastercrafttires.com/Tire-Saf...-Rotation.aspx .

Usually wear is even due to frequent swaps, if not I put the best tires rear and ignore swapping scheme.